Virtual movies are widely used for a variety of purposes, such as exhibitions, remote guidance and touring of places, education, training, electronic games, etc. Some of such movies are animated, and some others are real, in the sense of involving real frames that are photographed within a real, physical site and some combine a mixture of real and animated frames. (It should be noted herein that throughout this application the term “frame” is used to indicate a unitary view that is introduced to the user at a specific time unit. In this respect, it should be noted that there is no distinction as to how this frame is produced, whether by acquiring it fully from the multimedia content, or producing it from a previous frame by completing only the differences from that previous frame in a manner as some compression tools operate). The present invention relates to all such cases, but mostly to the latter case; i.e., to the case where the preparation of a virtual and interactive movie enables a user to interactively explore a real site; i.e., to a case in which a user wishes to watch a movie of a site, and navigate interactively within the site.
In recent years there have been extensive efforts to streamline the playing of multimedia over computer networks with no need of a full movie preload prior to a continuous playback. Throughout this application, a discussion is made to video movies (or clips), although some aspects of the invention may be relevant to other types of multimedia. Most existing solutions take into account the fact that the network bandwidth is limited, and that the speed of transfer dynamically varies. Some solutions suggest the reduction of the amount of data transferred (e.g., by means of compromising the media quality, or by means of compressing the data), and adjustment of the amount of data transferred to the network speed. The main objective is to obtain a smooth experience with maximum image quality for a given bandwidth. One common solution suggests the performing of a preload of a multimedia sequence (such as a movie clip), to balance the stream of the information loading during playback, in order to improve the availability of the clip portions at the user's station, and to prevent delays and suspensions. Throughout this application, the term “station” relates to any type of computer, processor, terminal, workstation, PDA, cellular phone, etc. which has a player for playing a content. Other factors that may affect the proper manner of handling multimedia information at the client side are the size of the data file and the amount of free storage at the user's end. Because the multimedia file at the remote (server) side is usually large, the fact that it cannot always be fully stored or fully preloaded to the client side must be taken in to account. In such a case, the user's experience may be hindered due to the need for a relatively long wait for the data he wishes to play.
The above prior art solutions are relatively satisfactory when playing a continuous conventional multimedia clip. However, such solutions cannot meet the stringent requirements of playing an interactive movie via a network of limited bandwidth. In a conventional movie the sequence of the movie frames is well defined, and therefore the maintaining of a FIFO type register at the user station can assist in the availability and integrity of the currently played sequence. However, this is not the case when playing an interactive virtual movie in which, during many stages of the movie, the user is given several options from which to select and continue with different sequences of the movie. This requirement to provide several video sequences to the user at any given time introduces a burden to the effective playing of an interactive virtual movie via the Internet (or any other bandwidth limited) network.
WO 2004/049263 by the same inventors discloses a method and system for the preparation of an interactive movie, which simulates the walking of a user within a real site and which enables a user to explore the site. Such a virtual movie can be streamed and displayed to a user relatively smoothly, in a high resolution and fast manner. However, any attempt to transfer and simultaneously display this interactive movie via a network, such as the Internet, at a station remote from the location in which the movie is stored, faces difficulties, particularly in satisfying the interactivity and smoothness requirements.
It is an object of the present invention to provide a method and system for the playing of a virtual movie via a bandwidth limited (sometimes very low bandwidth) network, such as the Internet.
It is another object of the invention to enable playing of such a movie in a manner that minimally affects the quality that the user experiences.
It is a particular object of the invention to enable the viewing via the Internet (or any other network) of a virtual movie for exploring a site.
Other objects and advantages of the invention will become apparent as the description proceeds.